Insertion effort.

<p>A) Mean number of combination of a correct key with its corresponding opening before insertion for each key within keyset A and B respectively (numbers above keys represent numbers of sides of symmetry) B) Mean duration (in seconds) of combination of a correct key with its corresponding opening before insertion for keyset A and B respectively. * above chance expectation; ** p<0.0001; t = n.s. trend: p<0.05 but not above chance after Bonferroni-Holms correction for multiple comparisons.